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-rw-r--r--fs/aio.c36
1 files changed, 32 insertions, 4 deletions
diff --git a/fs/aio.c b/fs/aio.c
index 12a3de0ee6da..2adbb0398ab9 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -112,6 +112,11 @@ struct kioctx {
struct work_struct free_work;
+ /*
+ * signals when all in-flight requests are done
+ */
+ struct completion *requests_done;
+
struct {
/*
* This counts the number of available slots in the ringbuffer,
@@ -508,6 +513,10 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
+ /* At this point we know that there are no any in-flight requests */
+ if (ctx->requests_done)
+ complete(ctx->requests_done);
+
INIT_WORK(&ctx->free_work, free_ioctx);
schedule_work(&ctx->free_work);
}
@@ -718,7 +727,8 @@ err:
* when the processes owning a context have all exited to encourage
* the rapid destruction of the kioctx.
*/
-static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
+static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
+ struct completion *requests_done)
{
if (!atomic_xchg(&ctx->dead, 1)) {
struct kioctx_table *table;
@@ -747,7 +757,11 @@ static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
if (ctx->mmap_size)
vm_munmap(ctx->mmap_base, ctx->mmap_size);
+ ctx->requests_done = requests_done;
percpu_ref_kill(&ctx->users);
+ } else {
+ if (requests_done)
+ complete(requests_done);
}
}
@@ -809,7 +823,7 @@ void exit_aio(struct mm_struct *mm)
*/
ctx->mmap_size = 0;
- kill_ioctx(mm, ctx);
+ kill_ioctx(mm, ctx, NULL);
}
}
@@ -1185,7 +1199,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
if (!IS_ERR(ioctx)) {
ret = put_user(ioctx->user_id, ctxp);
if (ret)
- kill_ioctx(current->mm, ioctx);
+ kill_ioctx(current->mm, ioctx, NULL);
percpu_ref_put(&ioctx->users);
}
@@ -1203,8 +1217,22 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
{
struct kioctx *ioctx = lookup_ioctx(ctx);
if (likely(NULL != ioctx)) {
- kill_ioctx(current->mm, ioctx);
+ struct completion requests_done =
+ COMPLETION_INITIALIZER_ONSTACK(requests_done);
+
+ /* Pass requests_done to kill_ioctx() where it can be set
+ * in a thread-safe way. If we try to set it here then we have
+ * a race condition if two io_destroy() called simultaneously.
+ */
+ kill_ioctx(current->mm, ioctx, &requests_done);
percpu_ref_put(&ioctx->users);
+
+ /* Wait until all IO for the context are done. Otherwise kernel
+ * keep using user-space buffers even if user thinks the context
+ * is destroyed.
+ */
+ wait_for_completion(&requests_done);
+
return 0;
}
pr_debug("EINVAL: io_destroy: invalid context id\n");